Method of applying protective tubing on pipes or the like



July 30, 1968 MOORE ETAL METHOD OF APPLYING PROTECTIVE TUBING ON PIPESOR THE LIKE Filed April 22, 1964 FIG.|

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INVENTORS LOUIS MOORE AND EDGAR H. BAKER BY 6 msq ATTORNEY United StatesPatent 3,394,444 METHOD OF APPLYING PROTECTH E TUBING M ON PIPES OR THELIKE Louis Moore and Edgar H. Baker, both of R0. Box 2726,

' Irondale Station, Birmingham, Ala. Continuation-impart of applicationSer. No. 149,098, Oct. 31, 1961. This application Apr. 22, 1964, Ser.No. 361,850

. 13 Claims. (til. 29157) The present case is a continuation in-part ofour copending application Ser. No. 149,098, entitled Method of ApplyingProtective Tubing on Pipe or the Like, filed Oct, 31, 1961, nowabandoned.

This invention relates to a method of applying protective coverings topipes.

More particularly, the invention contemplates the utilization of aprotective cover in connection with underground installations wherepipes, whether metallic, concrete, or produced from other materials, areof necessity subjected to corrosive and other adverse exteriorinfluences, thereby seriously affecting the life of such installations.

In s0-called hot soils, which may contain acids and/ or alkalis,metallic pipes deteriorate with relative rapidity, frequent repairs orreplacement being required. Similar considerations apply to metallic,concrete, or other pipes in installations where there are continuingconditions of dampness, whether by reason of substantial rainfall orneighboring naturally occurring flow of water.

It has been proposed, heretofore, to provide such pipes with a plasticprotective wrapping, certain polyoleiin films being well suited for suchpurposes. Such methods have not functioned satisfactorily since thewrapping pipes in situ is quite an extensive operation and, except wheresealing was employed, seepage with deleterious effects developed atoverlapping areas.

Applicants have discovered that these prior art problems can be overcomeif plastic'tubing is employed as the protective covering and such tubingcan be produced with particular ease and economy from such materials aspolyethylene, polypropylene, polyvinyl chloride, and the like, tubularfilms of this character being resistant to acids and a'lkalis and alsobeing water impermeable.

Corrosive problems as to metallic pipes have been referred to hereabove.An inherent weakness of concrete pipes generally manifests itself insoft-water soils wherein the excessive moisture and pH provide forgradual pipe disintegration. Thus, it will be understood that theplastic material selected for the protective covering will have dire-ctrelationship to the type of soil and surrounding conditions in which thepipe will rest.

It is a particular object of the invention to provide a novel methodwhereby pipes in underground installations, and the like, may beprovided with a fluid impermeable protective coating produced fromsuitable tubular plastic materials.

Further objects and advantages of the invention will be readily apparentfrom the following specifications, taken in conjunction with theaccompanying drawing wherein:

FIGURE 1 is a fragmentary longitudinal sectional view through anunderground pipe installation illustrating a plurality of connected pipelengths with the protective cover of the present invention appliedthereto in surrounding relationship, parts being broken away;

FIGURE 2 is a fragmentary sectional view illustrating somewhatdiagrammatically, an initial step in connection with the installation ofthe protective covering of the present invention;

FIGURE 3 is a transverse sectional view taken on the 'line"33 of FIGURE2;

3,394,444 Patented July 30, 1 968 FIGURE 4 is a side elev-ational viewillustrating, somewhat diagrammatically, a section of tubular protectivecover in longitudinally collapsed condition; and

FIGURE 5 is a side elevational view, similar to FIG- URE 4, of a sectionof protective tubing collapsed and secured by a tie cord or tape. 7

Briefly stated, the present invention contemplates the utilization of atubular protective pipe covering produced from suitable plasticmaterial, as by an extrusion process or otherwise, and collapsedsubstantially completely upon its longitudinal axis into a bellows-likeor accordion condition to permit the ready placement thereof insurrounding relationship upon a length of pipe to be covered. Desirablythe protective covering or tubing should be approximately two feet, orin excess thereof, longer than the section of pipe to be covered toprovide for an overlapping joint between opposed extremities of adjacentlengths of protective tubing. 7

As shown in the drawing, particular reference being had to FIGURE 1thereof, the protective tubing of the present invention may be producedfrom any suitable plastic material, including polyethylene,polypropylene, polyvinyl chloride, and the like, which is resistant toboth acids and alkalis and which is impermeable to fluids. Desirab'lysuch tubing may be produced by an extrusion process and severed intodesired lengths 10, the interior diameter thereof having relationship tothe exterior diameter of the pipe to be covered. It also is contemplatedthat such protective tubing may be produced from a continuous length ofplastic film having the longitudinal edges thereof united, as by aheat-sealing operation where the film is thermoplastic, as is well knownin this art.

For commercial use, in accordance with the present invention, eachlength of tubing 10 is collapsed upon itself, as illustrateddiagrammatically in FIGURES 4 and 5 of the drawing, along itslongitudinal axis, to pro vide a bellows or accordion likeconfiguration, except for the free extremities 10a and 10b. In thissubstantially completely collapsed condition there will be alternatingpeaks and valleys, or high and low points, and 10d and, since the tubingwith which we here are concerned has a high degree of flexibility, theseaccordion folds cannot be expected to provide any substantial degree ofregularity but will be achieved at random, it only being necessary thatthe collapsed annulus thus produced provide a free central opening ofsufficient diameter to pass freely over the pipe to be covered.

A partially collapsed length of tubing has been illustrated in FIGURE 4while a further collapsed length is shown in FIGURE 5 with a suitablefastening element or tie cord 11, or the like, applied thereto toprovide for convenient handling.

It also is within the scope of the present invention to produce thetubular covering by a molding operation in which event a truebellows-type structure will be created, having self-sustainingcharacteristics and readily expansible to an elongated tube having aninterior diameter corresponding to that of the free extremities 10a and1012.

A collapsed annulus of the character described may be placed upon alength of pipe to be covered, in encircling relationship, withparticular facility, and then extended to full length and secured incompletely protective position thereby obviating prior art difficultieswhere attempts have been made to utilize a flattened length of tubularmaterial for present purposes.

Installation of the protective covering preferably is accomplished insitu and means is provided for sealing at least one extremity of theprotective tubing to the pipe per se and for sealing the opposedextremities of adjacent lengths of said tubing to each other, therebyproviding a completely sealed covering for the pipe as will be describedmore fully hereafter.

As illustrated fragmentarily and diagrammatically in FIGURE 1 of thedrawing, the pipe 12 to be covered may be produced from any suitablematerial and of any exterior and interior diameters in accordance withthe specific requirements inherent to the end use or function of theinstallation. In the illustrative embodiment shown there are a pluralityof interconnected pipe lengths 12, each such length including anenlarged bell-shaped extremity 12a for the convenient reception of theopposed extremity or spigot end of the next adjacent pipe length 12, asis well known in this art, to provide a relatively smooth and continuousinterior surface with free flow therethrough.

A trench or the like 13 has been illustrated, and the pipe installation,as well as the protective covering thereof, is accomplished therein. Tofacilitate wrapping at each pipe section joint, the trench may beprovided with relatively shallow bell depressions or holes indicated at13a.

With the initial pipe section 12 in place, a collapsed length ofprotective tubing 10 is placed upon the next adjacent length of pipe 12which is suitably supported, as by a sling or the like, preparatory tolowering thereof into the trench 13. The pipe length 12 is then loweredinto the trench, the spigot end thereof is seated within the bellextremity 12a of the preceding pipe length, and the pipe joint is madeup in normal fashion. The sling then is removed from adjacent thecentral portion of the pipe length being covered and the hook isenagaged within the free bell cavity and this extremity of the pipelength is raised a sufficient distance, three to four inches will beentirely adequate, to permit the collapsed protective tubing to be drawnor slipped along the barrel of the pipe section to its complete ororiginal uncollapsed length with enough of the tubular covering beingretained, in bunched-up accordion condition at each extremity to overlapone foot, or possibly more, of the extremity of the adjacent oradjoining pipe section. As stated hereabove, the length of each lengthof protective tubing 10 is two to three feet (or more) greater than thelength of the pipe section to be covered, and these dimensions may varythrough a particularly extensive range; thus, ample material is providedfor the overlap contemplated.

The adjacent extremity 10b of the tubular covering 10 is then pulledover the bell of the pipe length to a position in surroundingrelationship with respect to the spigot extremity of the adjoining pipelength 12 and a suitable plastic adhesive tape 14 is employed to sealthe extremity of the tubular covering 10 to the surface of the pipesection 12. Desirably such tape should have a width approximating 2",include a plastic backing and have adhesive characteristics insuringready bonding with both pipe surface and tubular material employed. Suchtapes are commercially available, as Polyken 900 (polyethylene)Scotchrap No. 50 (polyvinyl), or the like, and three circumferentialturns thereof are viewed as entirely effective.

To make the overlap joint, thus completing the seal, the collapsedextremity 10a of the adjacent tubular covering 10 is pulled over thecovered bell 12a of the initial pipe length 12, folded around theadjacent pipe portion and sealed in place behind the bell portion, asindicated at 15, utilizing several (three, preferably) circumferentialturns of the 2 plastic adhesive tape referred to hereabove.

Fittings, valves, hydrants, etc., can be protectively covered bysplitting the tubular material, as may be necessary, and utilizingplastic adhesive tape for effecting a seal. The protective covering ofbends, reducers, and offsets occurring in pipe systems will present noproblems as the tubular material of the present invention may beemployed with equal facility in connection with such departures from acontinuous length of axially aligned pipe. It should be remembered thatall fittings which may require concrete backing should be wrappedcompletely prior to the pouring of the concrete block.

It will be understood that, in the practice of the present invention,the wrap or covering, particularly on the barrel portions of the pipesections will be relatively loose, thus permitting the plastic coveringmaterial to shift with the soil during filling of the trench orinstallation, as well as in the event of any subsequent undergroundmovement, thereby eliminating possibility of damage by shearing,abrasion, or the like.

As to the characteristics of the protective or tubular coveringmaterial, a thickness on the order of 8 mils has been found to be highlysatisfactory. Where polyethylene film is employed, such film should beproduced from virgin polyethylene having characteristics present inU.S.I. Petrothene or Du Pont Alathon resins. Films of this characterhave a tensile strength of from 1200 to 2500 psi. with an elongationfactor of up to 600% and are admirably suited for present purposes.

In such polyethylene films, the dielectric strength of 500 to 850 voltsper rail of thickness provides insulating characteristics which exceedvastly the esbtablished requirements of underground installations. Thereis no known corrosive soil condition which will affect polyethylenesince this material is chemically inert and, with a moisture absorptionfactor of less than 0.01% in 24 hours, such films constitute aparticularly effective seal against penetration by water or vapor.Further, there are no volatile constituents in polyethylene which mayescape and result in loss of ductility. Other advantages include thefact that in the event of any mischance which results in film ruptureafter installation, with application at the trench site likelihood ofdamage in transit is eliminated, whereby ground water enters between thefilm and pipe, this space becomes filled and reaction is, of necessity,spread over a relatively large area. Under such conditions, corrosionwill cease when the original quantity of electrolyte is neutralized.

There has thus been described a novel protective pipe covering, and anovel method of installation, whereby pipes and the like in undergroundor similar installations may be effectively guarded with particulareconomy against damage resulting through corrosion, deterioration orother adverse exterior influences. It will be obvious to those skilledin this art that various changes may be made in the invention withoutdeparting from the spirit and scope thereof and therefore the inventionis not considered limited by that which is shown in the drawing anddescribed in the specification and reference is had to the claims forsummaries of the essentials of the invention, of the novel features ofconstructions, and novel method of installation for all of whichprotection is desired.

What is claimed is:

1. A method of applying a protective covering to a pipe installationwhich comprises a plurality of connected pipe sections, said methodincluding the steps of placing upon the first pipe section insurrounding relationship with respect thereto a longitudinally collapsedfirst length of tubular plastic material which is of greater extendedlength than that of the pipe section to be covered; sealing the trailingextremity of said tubular material to the peripheral surface of saidpipe installation adjacent the trailing extremity of said first pipesection; longitudinally expanding said length of tubular material towardthe leading end of said first pipe section; placing a longitudinallycollapsed second length of tubular plastic material upon the second pipesection in surrounding relationship with respect thereto; creating ajoint between the trailing end of the second pipe section and theleading end of said first pipe section; further longitudinally expandingthe leading extremity of said first length of tubular material to coversaid joint; sealing the leading extremity of said first length to theadjacent peripheral surface of said second pipe section; expanding thetrailing end of the second length of tubular material on said secondpipe section rearwardly beyond the joint between said first and adjacentsecond pipe sections; sealing the trailing extremity of said secondlength of tubular material to the adjacent peripheral surface of thetubular material on said first pipe section; expanding said secondlength of tubular material toward the leading end of the second pipesection; and repeating the operative steps set forth for each successivepipe section.

2. The method of claim 1 where the seals between the tubular plasticmaterial and the peripheral surface of a pipe section, and the sealsbetween overlying layers of tubular plastic material, is created by atleast one turn of an adhesive tape of sufiicient width to bond to theextremity of the tubular material and to the surface to which saidmaterial is to be sealed.

3. The method of claim 1 where said tubular plastic material is apolyolefin.

4. The method of claim 1 where said tubular material is an extrudedpolyolefin.

5. The method of claim 4 where said tubular material is polyolefinhaving a thickness on the order of 8 mils.

6. The method of claim 5 where the tubular material is polyethylene.

7. The method of claim 1 where said protective covering is applied insitu to an underground pipe installation.

8. The method of protecting the outer surface of a pipe which includesthe steps of placing upon said pipe in surrounding relationship withrespect thereto a length of tubular plastic material which has beencollapsed along its longitudinal axis into a bellows-like condition;sealing the trailing extremity of said collapsed tubular material to theperipheral surface of said pipe adjacent the trailing extremity thereof;partially longitudinally expanding said collapsed length of tubularmaterial to a length slightly less than the complete length thereof;placing a second collapsed length of tubular material upon said pipe insurrounding relationship with respect thereto; sealing the trailingextremity of said second collapsed length of tubular material to theperipheral surface of said pipe at a point adjacent the leadingextremity of said partially expanded first length of tubular material;further expanding the leading extremity of said first length of tubularmaterial to surround the sealed trailing extremity of said second lengthof tubular material; sealing the leading extremity of said first lengthof tubular material to the peripheral surface of the underlying lengthof tubular material; and repeating the operative steps for eachsuccessive length of tubular material.

9. The method of claim 8 where the seals between the tubular plasticmaterial and the perihperal surface of a pipe section, and the sealsbetween overlying layers of tubular plastic material, is created by atleast one turn of an adhesive tape of sufiicient width to bond to theextremity of the tubular material and to the surface to which saidmaterial is to be sealed.

10. The method of claim 8 where said tubular plastic material is apolyolefin.

11. The method of claim 8 where said tubular material is an extrudedpolyolefin.

12. The method of claim 11 where said tubular material is polyolefinhaving a thickness on the order of 8 mils.

13. The method of claim 12 where the tubular material is polyethylene.

References Cited UNITED STATES PATENTS 2,007,969 7/ 1935 Grodsky 6172.12,272,704 2/ 1942 Harding.

2,907,351 10/ 1959 Rohrback et a1.

3,126,624 3/1964 Mirsky et a1. 29-450 3,049,801 8/ 1962 Workman 29-4503,065,531 11/1962 Rosenthal 29450 2,396,059 3/1946 Roberts 138-1222,622,623 12/ 1952 Michaudet 138122 CHARLIE T. MOON, Primary Examiner.

L. I. LENNY, Examiner.

8. THE METHOD OF PROTECTING THE OUTER SURFACE OF A PIPE WHICH INCLUDESTHE STEPS OF PLACING UPON SAID PIPE IN SURROUNDING RELATIONSHIP WITHRESPECT THERETO A LENGTH OF TUBULAR PLASTIC MATERIAL WHICH HAS BEENCOLLAPSED ALONG ITS LONGITUDINAL AXIS INTO A BELLOWS-LIKE CONDITION;SEALING THE TRAILING EXTREMITY OF SAID COLLAPSED TUBULAR MATERIAL TO THEPERIPHERAL SURFACE OF SAID PIPE ADJACENT THE TRAILING EXTREMITY THEREOF;PARTIALLY LONGITUDINALLY EXPANDING SAID COLLAPSED LENGTH OF SAID PIPEADJACENT LENGTH SLIGHTLY LESS THAN THE COMPLETE LENGTH THEREOF; PLACINGA SECOND COLLAPSED LENGTH OF TUBULAR MATERIAL UPON SAID PIPE INSURROUNDING RELATIONSHIP WITH RESPECT THERETO; SEALING THE TRAILINGEXTREMITY OF SAID SECOND COLLAPSED LENGTH OF TUBULAR MATERIAL TO THEPERIPHERAL SURFACE OF SAID PIPE AT A POINT ADJACENT THE LEADINGEXTREMITY OF SAID PARTIALLY EXPANDED FIRST LENGTH OF TUBULAR MATERIAL;FURTHER EXPANDING THE LEADING EXTERMITY OF SAID FIRST LENGTH OF TUBULARMATERIAL TO SURROUND THE SEALED TRAINING EXTREMITY OF SAID SECOND LENGTHOF TUBULAR MATERIAL; SEALING THE LEADING EXTREMITY OF SAID FIRST LENGTHOF TUBULAR MATERIAL TO THE PERIPHERAL SURFACE OF THE UNDERLYING LENGTHOF TUBULAR MATERIAL; AND REPEATING THE OPERATIVE STEPS FOR EACHSUCCESSIVE LENGTH OF TUBULAR MATERIAL.